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Re: [TowerTalk] Buried HF/VHF feedlines

To: kkbroadcastengineering@gmail.com, towertalk@contesting.com
Subject: Re: [TowerTalk] Buried HF/VHF feedlines
From: Jonathan - KE0YBL via TowerTalk <towertalk@contesting.com>
Reply-to: Jonathan - KE0YBL <KE0YBL@protonmail.com>
Date: Sun, 26 Jul 2020 00:15:55 +0000
List-post: <mailto:towertalk@contesting.com>
Thanks, appreciate the local feedback. Not to get too off topic, but I'm 
planning to run the conduit to pull boxes/hand holes on each end, then short 
runs to the shack and tower. Water management, easier pulls, etc.

Does anyone have recommended boxes? Sprinkler boxes seem pretty junky as far as 
lawn mower tires etc. Proper Oldcastle concrete boxes are a bit overkill price 
wise. Other favorites? Also other techniques for coming up from below frost 
level into the box? Presumably just gradual slope and into the side as with 
most other stuff..

Thanks,

Jonathan

-------- Original Message --------
On Jul 25, 2020, 6:55 PM, Kevin Kidd wrote:

> A few observations...
>
> Splices are "weather proof" not water proof and should never, ever, ever,
> ever, never be placed below grade or in a flooded conduit. They will too
> often leak hanging on a tower, they will always leak underground /
> underwater.
>
> I have pictures of 3in Air Heliax compressed to about half that diameter
> after freezing in a shallow, water filled, steel conduit in a MN swamp.
>
> Hardline is waterproof and direct burial as long as it hasn't been spliced
> or damaged. Bury the coax or conduit below the local frost line and don't
> splice it and you will be good for years.
>
> Good luck,
>
> Kevin C. Kidd, CSRE/AMD - WD4RAT
> kkbclists@kkbc.com <kkidd@kkbc.com>
> Lawrenceburg, TN
> KK Broadcast Engineering - AM Ground Systems Company
> www.kkbc.com -- www.amgroundsystems.com
>
> On Sat, Jul 25, 2020 at 1:26 AM Jonathan - KE0YBL via TowerTalk <
> towertalk@contesting.com> wrote:
>
>> Hi All,
>> I feel like this has been done to death - and yet, the Internet has really
>> been notoriously awful with misinformation for me the past few weeks. I
>> appreciate your thoughts as I work through this!
>>
>> I'm putting up a new tower primarily for HF and maybe some VHF. Given my
>> ideal location is some ~350ft+ from the shack, I've been waffling back and
>> forth as to whether to remote the radios in an enclosure, or bring Heliax
>> back. I'm leaning toward the Heliax route.
>>
>> I'm working with an experienced (decades) climber/tower company in my area
>> (Minnesota), who has used 7/8" Heliax for $1.50/ft. This seems reasonable,
>> and a fraction of new, thus making my project seem doable. Sadly may
>> require an underground splice due to lengths, but one battle at a time. I'm
>> open to other sources for such things.
>>
>> Herein lies the rub -- my climber's experience has been (and probably
>> yours as well) that directly burying this in our frozen tundra eventually
>> results in crushed cable through thawing and freezing. I'm considering 3"
>> or 4" HDPE conduit/innerduct to alleviate that, but given I'll need to go
>> through a valley, condensate will condensate in the dip no matter what I
>> do. I could perhaps drop the conduit down 36+" deep to avoid the frost
>> level, but it'll still be sitting in water (albeit not frozen at that
>> depth) without active moisture management in the run (fan, nitrogen (ugh),
>> whatever - not feasible).
>>
>> I feel like at this point I'm really overthinking it. Fiber to the tower
>> and radios in a box would be much easier, but less desirable - but now I'm
>> really torn.
>>
>> I appreciate your feedback immensely,
>>
>> Jonathan
>> _______________________________________________
>>
>>
>>
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